"We've shuffled the deck for a number of reasons," San Diego manager Bud Black said. "We didn't get off to a good start. The last month, we've been better. It's not ideal, but that's where we stand."

The loss left San Diego at 19 games under .500.

"It's been an up-and-down first half," center fielder Cameron Maybin said. "We just got to continue to compete, continue to grind."

Bruce and Ludwick connected two pitches apart in the fourth inning to give Cincinnati a 3-0 lead.

Ludwick played for San Diego for about one full season from the time he was traded by St. Louis during the 2010 season until the Padres dealt him to Pittsburgh at the trading deadline last year.

He had little success hitting at pitcher-friendly Petco Park.

"This is a new year," Ludwick said. "I feel like I'm hitting the ball a little bit differently. I think everyone knows that I kind of got pulled down a bit when I was here. I'm hitting the ball better now."

Cueto (10-5), who felt snubbed when he was not picked for the NL All-Star team, looked solid until he ran into trouble in the sixth inning.

Cueto gave up two runs on seven hits in 5 2-3 innings and was pulled after issuing a bases-loaded walk. The right-hander struck out five, walked two, and hit two batters.

Brandon Phillips led off the Reds fourth with a single and Bruce connected against Jason Marquis (1-5) for his 18th home run. Ludwick followed with his 12th home run, a shot into the second deck in left field.

"I felt like I was executing like I wanted to, getting quick outs," Marquis said. "I fell behind to Bruce and he capitalized on my mistake."

The Reds came close to another home in the fifth run when Joey Votto, the NL All-Star starting first baseman, hit a deep drive into left-center field. Center fielder Cameron Maybin took a running leap and snared the ball right at the top of the wall just as he crashed into the padding.

"I was just positioned in the right spot," Maybin said. "I got a good jump and saw where the wall was."

Trailing 3-1, San Diego loaded the bases in the sixth with two outs on three singles. Pinch hitter Mark Kotsay fouled off three straight pitches with a full count before he drew a walk from Cueto.

Reliever Sam LeCure came in and retired Chris Denorfia on a fly ball.

Zack Cozart doubled and scored on Phillips' single in the seventh. It was Cozart's 21st double, the most by a rookie shortstop prior to the All-Star break, breaking the mark set by Boston's Nomar Garciaparra in 1997.

Marquis allowed three runs on seven hits in five innings. The righty struck out five and did not walk a batter while making consecutive starts on three days' rest for the fifth time in his career.

Marquis is 1-9 in his last 11 starts.

NOTES: After scoring one run in each of three consecutive defeats, the Reds scored 16 runs in the last three games at San Diego. ... The Padres have lost only one of their last five series.